Turn Signal Lamps and/or Indicators Malfunction
Turn Signal Lamps and/or Indicators Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Ground is applied at all times at G201 to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed ON and OFF.
Reference Information
Schematic Reference
* Exterior Lights Schematics Exterior Lights Schematics
* Body Control System Schematics [1][2]Body Control Systems
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Right and Left Turn Signal Switch parameters while cycling the turn signal switch between the left and right positions. The parameters should change between Active and Inactive.
• If the parameters do not change between the commanded states, refer to Turn Signal Switch Malfunction.
2. Command the right and left turn signal lamps ON and OFF with the turn signal switch. The left and right turn signal lamps should turn ON and OFF when changing between the commanded states.
• If the right or left turn signal lamps do not turn ON and OFF when changing between the commanded states, refer to Turn Signal Lamps Malfunction.
3. Command the Display Test ON and OFF with a scan tool. The left and right turn signal indicators should turn ON and OFF when changing between the commanded states.
• If the left and right turn signal indicators do not turn ON and OFF when commanded, refer to Turn Signal Indicators Malfunction.
Circuit/System Testing
Turn Signal Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multifunction switch.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal 1 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 8 for a short to ground. If the circuit tests normal, replace the K9 body control module.
4. Verify the scan tool Right Turn Signal Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the K9 body control module.
5. Install a 3A fused jumper wire between the signal circuit terminal 8 and ground. Verify the scan tool Left Turn Signal Switch parameter is Active.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 body control module.
6. Install a 3A fused jumper wire between the signal circuit terminal 7 and ground. Verify the scan tool Right Turn Signal Switch parameter is Active.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 body control module.
7. If all circuits test normal, replace the S78 turn signal/multifunction switch.
Turn Signal Lamps Malfunction
1. Ignition OFF, disconnect the X4 harness connector at the K9 body control module.
2. Verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
5. Ignition OFF, connect the X4 harness connector at the K9 body control module.
6. Disconnect the harness connector at the inoperative turn signal lamp.
7. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground:
* E13L headlamp - left terminal 1
* E13R headlamp - right terminal 1
* E42L tail lamp assembly - left terminal 2
* E42R tail lamp assembly - right terminal 2
• If greater than the specified range, test the ground circuit for an open/high resistance.
8. Connect a test lamp between the appropriate control circuit terminal listed below and ground.
* E13L headlamp - left terminal 9
* E13R headlamp - right terminal 9
* E42L tail lamp assembly - left terminal 4
* E42R tail lamp assembly - right terminal 4
9. Command the appropriate Turn Signal Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 body control module.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 body control module.
10. If all circuits test normal, replace the inoperative turn signal lamp.
Turn Signal Indicators Malfunction
Ignition ON, with a scan tool perform the Display Test for the instrument panel cluster (IPC) and observe the turn signal lamp indicators.
If the turn signal lamp indicators illuminate during the test, replace the K9 body control module.
If the turn signal lamp indicators do not illuminate during the test or remain illuminated at all times, replace the P16 instrument cluster.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Parking and Turn Signal Lamp Replacement Service and Repair
* Stop and Tail Lamp Bulb Replacement Stop and Tail Lamp Bulb Replacement
* Turn Signal Switch Replacement Service and Repair
* Control Module References Control Module References for BCM or IPC replacement, setup, and programming